Skin materials produced by use of a soft polyvinyl chloride resin composition are inexpensive and excellent in flexibility and scratch resistance. Therefore, the skin materials have widely been used hitherto in fields of automobile interior members such as instrument panels, door trims, console boxes and seats, furniture such as sofas and chairs, and so on. At the time of producing these skin materials, there has been popularly used slush molding, wherein a powdery polyvinyl chloride resin composition is stuck onto the surface of a mold having a complicated shape and then the composition is heated and molded, in the prior art. Since soft polyvinyl chloride resin powder is inexpensive and excellent in flexibility and can be fashioned into a complicated shape, the powder has widely been used also in the production of toys and others by rotational molding.
However, polyvinyl chloride resin generates harmful substances such as dioxin when the resin is incinerated, and further it is suspected that a plasticizer used therein acts as environmental disrupter, carcinogens, or the like. Thus, the resin has problems about environmental pollution and safety. There are also caused problems, such as bleed-out and fogging resulting from the plasticizer.
In light of the above-mentioned points, investigation has been made in recent years about the matter that a thermoplastic elastomer which does not contain any halogen or any plasticizer is used instead of polyvinyl chloride resin and the elastomer is subjected to slush molding.
Of molding methods and coating methods using powder, slush molding or rotational molding is performed without applying any fashioning pressure. It is therefore necessary that powdery material stuck onto a mold at the time of molding is melted and flows under no applied pressure so as to form a coating. From this viewpoint, the thermoplastic elastomer powder used in slush molding or rotational molding has a requirement that the melt viscosity thereof is low under low shearing.
As the thermoplastic elastomer powder which is low in melt viscosity under low shearing, has fluidity even under conditions that no fashioning pressure is applied and further can be applied to slush molding, there is known a thermoplastic elastomer powder for slush molding which is made of an elastomer composition of an ethylene/α-olefin copolymer rubber and a polyolefin resin (see JP-A-5-5050). However, the thermoplastic elastomer powder for slush molding described in the JP-A-5-5050 is a nonpolar resin; therefore, the powder is low in adhesion to polar resins such as polyurethane resin and ABS resin, and thus a composite body or the like which is composed of the elastomer and a polar resin is not easily produced. A molded product obtained from this thermoplastic elastomer powder is not sufficiently satisfactory in flexibility.
As the material for slush molding which exhibits adhesion to polar resins, suggested is a material for slush molding which comprises a thermoplastic polyurethane elastomer, a plasticizer, a block polyisocyanate, and a pigment (JP-A-11-49948). However, this material for slush molding has a problem that the plasticizer, which is used to keep low-temperature properties, melt fluidity, flexibility and others, causes bleed-out or fogging in the same manner as the flexible polyvinyl chloride resin powder, and other problems. This material for slush molding is also low in weatherability since the base thereof is the polyurethane elastomer.
An object of the present invention is to provide a thermoplastic polymer powder which: is good in melt fluidity; can be used suitably for molding techniques using powder, such as slush molding and rotational molding, powder coating techniques and the like; does not contain any halogen nor any plasticizer; does not cause environmental pollution or anxiety about carcinogenicity; and can be further made into a high-quality molded product, skin material or painted film excellent in weatherability, flexibility, rubber elasticity, low-temperature properties, adhesion to polar resins, texture, external appearances and others.
Another object of the present invention is to provide a molded product obtained from the thermoplastic polymer powder, and a process for producing the same.